1. Field of the Invention
The present process is directed to the production of dinitriles and more particularly, to an improvement in the method of hydrocyanating 3- and/or 4-pentenenitriles in the presence of a zero-valent nickel catalyst to produce adiponitrile.
2. Description of the Prior Art
U.S. Pat. No. 3,496,218 issued on Feb. 17, 1970 describes in general terms a process for the preparation of dinitriles especially adiponitrile by the hydrocyanation of non-conjugated, ethylenically unsaturated organic compounds, e.g., 3- and/or 4-pentenenitriles using certain nickel complexes as catalysts. The catalysts are promoted by organoborane compounds such as triphenylborane. A wide range of process conditions and relative amounts and types of reactants are disclosed. Other operable promoters are described in U.S. Pat. No. 3,496,217 issued on Feb. 17, 1970.
A particularly useful form of zero-valent nickel catalyst is described in U.S. Pat. No. 3,766,237 issued on Oct. 16, 1973. The patentees disclose the use of an excess of the triarylphosphite ligand in the hydrocyanation along with the addition of certain ethers to improve the yield and increase the pounds of product which can be made per pound of catalyst consumed.
U.S. Pat. No. 4,082,811 issued on Apr. 4, 1978 discloses a hydrocyanation process coupled with a method for recovery of catalyst.